Effects of hyperbaric oxygen treatment on antimicrobial function and apoptosis of differentiated HL-60 (neutrophil-like) cells

Effects of Pressure, Hypoxia, and Hyperoxia on Neutrophil Granulocytes

Background: The application of normo- and hyperbaric O2 is a common therapy option in various disease patterns. Thereby, the applied O2 affects the whole body, including the blood and its components. This study investigates influences of pressure and oxygen fraction on human blood plasma, nutrient media, and the functions of neutrophil granulocytes (PMNs). Methods: Neutrophil migration, reactive oxygen species (ROS) production, and NETosis were examined by live cell imaging. The treatment of various matrices (Roswell Park Memorial Institute 1640 medium, Dulbecco's Modified Eagle's Medium, H2O, human plasma, and isolated PMNs) with hyperbaric oxygen (HBO) was performed. In addition, the expression of different neutrophil surface epitopes (CD11b, CD62L, CD66b) and the oxidative burst were investigated by flow cytometry (FACS). The application of cold atmospheric plasma (CAP) to normoxic and normobaric culture media served as a positive control. Soluble reaction products such as H2O2, reactive nitrogen species (RNS: NO2- and NO3-), and ROS-dependent dihydrorhodamine oxidation were quantified by fluoro- and colorimetric assay kits. Results: Under normobaric normoxia, PMNs migrate slower and shorter in comparison with normobaric hyper- or hypoxic conditions and hyperbaric hyperoxia. The pressure component has less effect on the migration behavior of PMNs than the O2 concentration. Individual PMN cells produce prolonged ROS at normoxic conditions. PMNs showed increased expression of CD11b in normobaric normoxia, lower expression of CD62L in normobaric normoxia, and lower expression of CD66b after HBO and CAP treatment. Treatment with CAP increased the amount of ROS and RNS in common culture media. Conclusions: Hyperbaric and normobaric O2 influences neutrophil functionality and surface epitopes in a measurable way, which may have an impact on disorders with neutrophil involvement. In the context of hyperbaric experiments, especially high amounts of H2O2 in RPMI after hyperbaric oxygen should be taken into account. Therefore, our data support a critical indication for the use of normobaric and hyperbaric oxygen and conscientious and careful handling of oxygen in everyday clinical practice.

Chitosan-based multifunctional oxygenating antibiotic hydrogel dressings for managing chronic infection in diabetic wounds

Current treatment strategies for infection of chronic wounds often result in compromised healing and necrosis due to antibiotic toxicity, and underlying biomarkers affected by treatments are not fully known. Here, a multifunctional dressing was developed leveraging the unique wound-healing properties of chitosan, a natural polysaccharide known for its numerous benefits in wound care. The dressing consists of an oxygenating perfluorocarbon functionalized methacrylic chitosan (MACF) hydrogel incorporated with antibacterial polyhexamethylene biguanide (PHMB). A non-healing diabetic infected wound model with emerging metabolomics tools was used to explore the anti-infective and wound healing properties of the resultant multifunctional dressing. Direct bacterial bioburden assessment demonstrated superior antibacterial properties of hydrogels over a commercial dressing. However, wound tissue quality analyses confirmed that sustained PHMB for 21 days resulted in tissue necrosis and disturbed healing. Therefore, a follow-up comparative study investigated the best treatment course for antiseptic application ranging from 7 to 21 days, followed by the oxygenating chitosan-based MACF treatment for the remainder of the 21 days. Bacterial counts, tissue assessments, and lipidomics studies showed that 14 days of application of MACF-PHMB dressings followed by 7 days of MACF dressings provides a promising treatment for managing infected non-healing diabetic skin ulcers.

Efficacy and safety of hyperbaric oxygen therapy for long COVID: a protocol for systematic review and meta-analysis

INTRODUCTION

There is still a lack of therapeutic options for long COVID. Several studies have shown the benefit of hyperbaric oxygen therapy (HBOT) on long COVID. However, the efficacy and safety of HBOT for long COVID remain unclear. Therefore, we will conduct this systematic review to assess the feasibility of HBOT as a primary or complemental therapy for long COVID.

METHODS AND ANALYSIS

Databases such as Web of Science, PubMed, Embase, Cochrane Database of Systematic Reviews, ClinicalTrials.gov, International Clinical Trials Registry Platform, Wanfang Database, China National Knowledge Infrastructure, SINOMED, VIP Database and the Chinese Clinical Trial Registry will be searched systematically from the establishment to 9 December 2023. All articles will be reviewed by two independent reviewers. Cochrane risk of bias tool will be used to assess the risk of bias in the study. We will evaluate heterogeneity using a visual inspection of the funnel plot. If an available number of studies are identified, we will perform a meta-analysis.

ETHICS AND DISSEMINATION

No ethical approval is required since this study is based on published articles. The findings will be published in a peer-reviewed journal or disseminated through conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42023482523.

A review on the research progress on non-pharmacological therapy of Helicobacter pylori

Helicobacter pylori is a pathogenic microorganism that mainly resides in the human stomach and is the major cause of chronic gastritis, peptic ulcer and gastric cancer. Up to now, the treatment of Helicobacter pylori has been predominantly based on a combination of antibiotics and proton pump inhibitors. However, the increasing antibiotic resistance greatly limits the efficacy of anti-Helicobacter pylori treatment. Turning to non-antibiotic or non-pharmacological treatment is expected to solve this problem and may become a new strategy for treating Helicobacter pylori. In this review, we outline Helicobacter pylori's colonization and virulence mechanisms. Moreover, a series of non-pharmacological treatment methods for Helicobacter pylori and their mechanisms are carefully summarized, including probiotics, oxygen-rich environment or hyperbaric oxygen therapy, antibacterial photodynamic therapy, nanomaterials, antimicrobial peptide therapy, phage therapy and modified lysins. Finally, we provide a comprehensive overview of the challenges and perspectives in developing new medical technologies for treating Helicobacter pylori without drugs.

Modulatory Contribution of Oxygenating Hydrogels and Polyhexamethylene Biguanide on the Antimicrobial Potency of Neutrophil-like Cells

Neutrophils are a first line of host defense against infection and utilize a series of oxygen-dependent processes to eliminate pathogens. Research suggests that oxygen availability can improve anti-infective mechanisms by promoting the formation of reactive oxygen species. Also, oxygen can synergistically upregulate the antibacterial properties of certain antibiotics against bacteria by altering their metabolism and causing an increase in the antibiotic uptake of bacteria. Therefore, understanding the effects of oxygen availability, as provided via a biomaterial treatment alone or along with potent antibacterial agents, on neutrophil functions can lead us to the development of new anti-inflammatory and anti-infective approaches. However, the study of neutrophil functions in vitro is often limited by their short life span and nonreproducibility, which suggests the need for cell line-based models as a substitute for primary neutrophils. Here, we took advantage of the differentiated human leukemia-60 cell line (HL-60), as an in vitro neutrophil model, to test the effects of local oxygen and antibacterial delivery by fluorinated methacrylamide chitosan (MACF) hydrogels incorporated with polyhexamethylene biguanide (PHMB) antibacterial agent. Considering the natural modes of neutrophil actions to combat bacteria, we studied the impact of our dual functioning oxygenating-antibacterial platforms on neutrophil phagocytosis and antibacterial properties as well as the formation of neutrophil extracellular traps (NETs) and reactive oxygen species (ROS). Our results demonstrated that supplemental oxygen and antibacterial delivery from MACF-PHMB hydrogel platforms upregulated neutrophil antibacterial properties and ROS production. NET formation by neutrophils upon treatment with MACF and PHMB varied when chemical and biological stimuli were used. Overall, this study presents a model to study immune responses in vitro and lays the foundation for future studies to investigate if similar responses also occur in vivo.

Hyperbaric oxygen therapy for healthy aging: From mechanisms to therapeutics

Hyperbaric oxygen therapy (HBOT), a technique through which 100% oxygen is provided at a pressure higher than 1 atm absolute (ATA), has become a well-established treatment modality for multiple conditions. The noninvasive nature, favorable safety profile, and common clinical application of HBOT make it a competitive candidate for several new indications, one of them being aging and age-related diseases. In fact, despite the conventional wisdom that excessive oxygen accelerates aging, appropriate HBOT protocols without exceeding the toxicity threshold have shown great promise in therapies against aging. For one thing, an extensive body of basic research has expanded our mechanistic understanding of HBOT. Interestingly, the therapeutic targets of HBOT overlap considerably with those of aging and age-related diseases. For another, pre-clinical and small-scale clinical investigations have provided validated information on the efficacy of HBOT against aging from various aspects. However, a generally applicable protocol for HBOT to be utilized in therapies against aging needs to be defined as a subsequent step. It is high time to look back and summarize the recent advances concerning biological mechanisms and therapeutic implications of HBOT in promoting healthy aging and shed light on prospective directions. Here we provide the first comprehensive overview of HBOT in the field of aging and geriatric research, which allows the scientific community to be aware of the emerging tendency and move beyond conventional wisdom to scientific findings of translational value.

Potential Advances of Adjunctive Hyperbaric Oxygen Therapy in Infective Endocarditis

Patients with infective endocarditis (IE) form a heterogeneous group by age, co-morbidities and severity ranging from stable patients to patients with life-threatening complications with need for intensive care. A large proportion need surgical intervention. In-hospital mortality is 15-20%. The concept of using hyperbaric oxygen therapy (HBOT) in other severe bacterial infections has been used for many decades supported by various preclinical and clinical studies. However, the availability and capacity of HBOT may be limited for clinical practice and we still lack well-designed studies documenting clinical efficacy. In the present review we highlight the potential beneficial aspects of adjunctive HBOT in patients with IE. Based on the pathogenesis and pathophysiological conditions of IE, we here summarize some of the important mechanisms and effects by HBOT in relation to infection and inflammation in general. In details, we elaborate on the aspects and impact of HBOT in relation to the host response, tissue hypoxia, biofilm, antibiotics and pathogens. Two preclinical (animal) studies have shown beneficial effect of HBOT in IE, but so far, no clinical study has evaluated the feasibility of HBOT in IE. New therapeutic options in IE are much needed and adjunctive HBOT might be a therapeutic option in certain IE patients to decrease morbidity and mortality and improve the long-term outcome of this severe disease.

The Effect of Hyperbaric Oxygen Therapy on Markers of Oxidative Stress and the Immune Response in Healthy Volunteers

Hyperbaric oxygen therapy (HBOT) consists of breathing 100% oxygen under increased ambient pressure. There are indications that HBOT induces oxidative stress and activates immune pathways. However, previous research on immunological effects of HBOT has mainly been established in in vitro experiments and selected patient populations, limiting generalizability and increasing the chances of confounding by comorbidities and specific patient-related factors. More insight into the immunological effects of HBOT would aid investigation and comprehension of potentially novel treatment applications. Therefore, in this study, we investigated the effects of three 110-min HBOT-sessions with 24-h intervals on immunological parameters in healthy, young, male volunteers. Blood samples were obtained before and after the first and third HBOT sessions. We assessed neutrophilic reactive oxygen species (ROS) production, systemic oxidative stress [plasma malondialdehyde (MDA) concentrations] as well as neutrophil phagocytic activity, plasma concentrations of tumor necrosis factor (TNF), interleukin (IL)-6, IL-8, and IL-10, and production of TNF, IL-6, and IL-10 by leukocytes ex vivo stimulated with the Toll-like receptor (TLR) ligands lipopolysaccharide (TLR4) and Pam3Cys (TLR2). We observed decreased neutrophilic ROS production and phagocytosis following the second HBOT session, which persisted after the third session, but no alterations in MDA concentrations. Furthermore, plasma concentrations of the investigated cytokines were unaltered at all-time points, and ex vivo cytokine production was largely unaltered over time as well. These results indicate no induction of systemic oxidative stress or a systemic inflammatory response after repeated HBOT in healthy volunteers but may suggest exhaustion of ROS generation capacity and phagocytosis.

Hyperbaric oxygen influences chronic wound healing – a cellular level review

Chronic wound is a serious medical issue due to its high prevalence and complications; hyperbaric oxygen therapy (HBOT) is also considered in comprehensive treatment. Clinical trials, including large meta-analyses bring inconsistent results about HBOT efficacy. This review is summarizing the possible effect of HBOT on the healing of chronic wound models at the cellular level. HBOT undoubtedly escalates the production of reactive oxygen and nitrogen radicals (ROS and RNS), which underlie both the therapeutic and toxic effects of HBOT on certain tissues. HBOT paradoxically elevates the concentration of Hypoxia inducible factor (HIF) 1 by diverting the HIF-1 degradation to pathways that are independent of the oxygen concentration. Elevated HIF-1 stimulates the production of different growth factors, boosting the healing process. HBOT supports synthesis of Heat shock proteins (HSP), which are serving as chaperones of HIF-1. HBOT has antimicrobial effect, increases the effectiveness of some antibiotics, stimulates fibroblasts growth, collagen synthesis and suppresses the activity of proteolytic enzymes like matrix metalloproteinases. All effects of HBOT were investigated on cell cultures and animal models, the limitation of their translation is discussed at the end of this revie

Predicting hyperbaric oxygen therapy success using the decision tree approach

Introduction

Hyperbaric oxygen therapy (HBOT), a procedure that involves the patient inhaling 100% oxygen gas under pressure, is currently used as an adjunctive treatment option for certain inflammatory conditions. HBOT can improve wound healing by increasing the rate of angiogenesis in injured tissue by increasing levels of vascular endothelial growth factor (VEGF). VEGF causes re-epithelialization, the migration of endothelial cells, and the formation of granulation tissue, which are involved in the wound healing process.

Methods

This study contains secondary data analyses of information previously collected in two separate studies, each concerning the effects of HBOT on diabetic foot ulcers and crush injury fractures at Prof. Dr. R. D. Kandou Hospital Manado and Siloam Hospital Manado from 2019 to early 2020.

Results

Based on the classification tree analysis, the predictors of HBOT success were leukocytes level (34%), platelet count (32%), and age (26%). The conditional inference tree analysis also indicated significant leukocyte levels, age, and platelet counts (p < 0.001), with which the interpretation of these results was the same as the classification tree analysis method. The results obtained from the random forest analysis revealed that the mean value of Gini reduction for leukocytes (207.3), platelets (110.2), age (97.9), and hemoglobin (57.9) can be used as indicators of successful HBOT. These three methods support that age, leukocytes, and platelets are determinants of HBOT success, while hemoglobin levels were only significant in one analysis method. Therefore, a new, proposed algorithm containing these factors was assembled from the results of this study.

Conclusion

HBOT cannot be separated from specific variables that contribute to and can predict its success.

Anti-biofilm Approach in Infective Endocarditis Exposes New Treatment Strategies for Improved Outcome

Infective endocarditis (IE) is a life-threatening infective disease with increasing incidence worldwide. From early on, in the antibiotic era, it was recognized that high-dose and long-term antibiotic therapy was correlated to improved outcome. In addition, for several of the common microbial IE etiologies, the use of combination antibiotic therapy further improves outcome. IE vegetations on affected heart valves from patients and experimental animal models resemble biofilm infections. Besides the recalcitrant nature of IE, the microorganisms often present in an aggregated form, and gradients of bacterial activity in the vegetations can be observed. Even after appropriate antibiotic therapy, such microbial formations can often be identified in surgically removed, infected heart valves. Therefore, persistent or recurrent cases of IE, after apparent initial infection control, can be related to biofilm formation in the heart valve vegetations. On this background, the present review will describe potentially novel non-antibiotic, antimicrobial approaches in IE, with special focus on anti-thrombotic strategies and hyperbaric oxygen therapy targeting the biofilm formation of the infected heart valves caused by Staphylococcus aureus. The format is translational from preclinical models to actual clinical treatment strategies.

Trichinella spiralis Calreticulin S-Domain Binds to Human Complement C1q to Interfere With C1q-Mediated Immune Functions

Helminths develop strategies to escape host immune responses that facilitate their survival in the hostile host immune environment. Trichinella spiralis, a tissue-dwelling nematode, has developed a sophisticated strategy to escape complement attack. Our previous study demonstrated that T. spiralis secretes calreticulin (TsCRT) to inhibit host classical complement activation through binding to C1q; however, the C1q binding site in TsCRT and the specific mechanism involved with complement-related immune evasion remains unknown. Using molecular docking modeling and fragment expression, we determined that TsCRT-S, a 153-aa domain of TsCRT, is responsible for C1q binding. Recombinant TsCRT-S protein expressed in Escherichia coli had the same capacity to bind and inhibit human C1q-induced complement and neutrophil activation, as full-length TsCRT. TsCRT-S inhibited neutrophil reactive oxygen species and elastase release by binding to C1q and reduced neutrophil killing of newborn T. spiralis larvae. Binding of TsCRT-S to C1q also inhibited formation of neutrophil extracellular traps (NETs), which are involved in autoimmune pathologies and have yet to be therapeutically targeted. These findings provide evidence that the TsCRT-S fragment, rather than the full-length TsCRT, is a potential target for vaccine or therapeutic development for trichinellosis, as well as for complement-related autoimmune disease therapies.

Effect of Hyperbaric Oxygen Therapy on Acute Liver Injury and Survival in a Rat Cecal Slurry Peritonitis Model

BACKGROUND

The effects of hyperbaric oxygen therapy (HBOT) in sepsis remain unclear. This study evaluated its effects on acute liver injury and survival in a rat model.

METHODS

Cecal slurry peritonitis was induced in male rats, which were then randomly allocated into the HBOT and control groups. In the survival experiment, six 90 min HBOT sessions (2.6 atmospheres absolute 100% oxygen) were performed over 48 h; the survival rate was determined 14 days after sepsis induction. In the acute liver injury experiment, three HBOT sessions were performed, followed by liver and plasma harvesting, 24 h after sepsis induction. Serum levels of alanine aminotransferase (ALT), interleukin (IL)-6, and IL-10 were measured, and the hepatic injury scores were determined. Reactive oxygen species (ROS) generation was detected by 2',7'-dihydrodichlorofluorescein diacetate (H2DCF-DA) assay. Western blot assays assessed protein kinase B (Akt), phosphorylated-Akt (p-Akt), glycogen synthase kinase (GSK)-3β, phosphorylated-GSK-3β, and cleaved caspase-3 levels.

RESULTS

Survival in the HBOT group (57.1%) was significantly higher than that in the controls (12.5%, p = 0.029), whereas IL-6, IL-10, and ALT levels were significantly lower in the HBOT group. The ROS generation was significantly inhibited to a greater extent in the HBOT group than in the control group. Additionally, in the HBOT group, the p-Akt and p-GSK-3β increased significantly and cleaved caspase-3 levels decreased significantly.

CONCLUSIONS

HBOT showed a beneficial effect on acute liver injury and rat survival by enhancing the Akt signaling pathway and decreasing apoptosis.

Hyperbaric oxygen treatment: A complementary treatment modality of Modic changes?

Modic changes (MCs) have attracted great interest in recent years. The complex process of MC development and progression seems to involve interplay between mechanical, infective, inflammatory, and degenerative processes that cannot be clearly differentiated. Based on signal intensity on T1- and T2-weighted MRI scans, MCs can be divided three types: Type 1, Type 2, and Type 3. Predominantly Type 1 MCs are commonly associated with chronic low back pain that is unresponsive to classic treatment options. Infection with low-virulent anaerobic microorganisms, most commonly Propionibacterium acnes, has been implicated in MC development following a disc herniation when a tear enables bacteria to enter the disc. Recent studies in patients with chronic low back pain following a lumbar disc herniation associated with Type 1 MCs have reported promising results following prolonged systemic antibiotic treatment with amoxicillin-clavulanate. Hyperbaric oxygen therapy, as primary or adjuvant treatment in association combination with systemic antibiotics or anti-inflammatory therapy, could offer important advantages in treating patients with suspected low-virulent disc infections due to anaerobic microorganisms associated with Type 1 MCs. We believe that hyperbaric oxygenation could contribute to faster resolution of Type 1 MCs and associated pain through multiple effects-including direct antimicrobial effects through formation of reactive oxygen species (ROS), altering the favorable low oxygen tension milieu such that it becomes unfavorable for bacterial growth and survival, and anti-biofilm effects. Additionally, hyperbaric oxygenation could contribute to faster pain resolution via direct and indirect anti-inflammatory effects. As an adjuvant treatment administered in combination with systemic antibiotics, HBOT could increase the sensitivity of Propionibacterium acnes to antimicrobial drugs under hyperoxic conditions, resulting in faster MC resolution. Overall, the faster infection resolution, diminished bacterial load, and anti-inflammatory effects due to reduced cytokine expression and levels of infectious by-products could lead to faster pain resolution following HBOT, and a significant improvement of quality of life in these patients.

Berberine Maintains the Neutrophil N1 Phenotype to Reverse Cancer Cell Resistance to Doxorubicin

This study explores the contributions of neutrophils to chemotherapeutic resistance and berberine-regulated cancer cell sensitivity to doxorubicin (DOX). In vitro experiments, continuous DOX treatment led to the shift of HL-60 cells to N2 neutrophils and thus induced chemotherapeutic resistance. The combination treatment with DOX and 2 µM berberine resulted in the differentiation of HL-60 cells toward N1 and therefore stimulated HL-60 cell immune clearance. Berberine increased reactive oxygen species (ROS) and decreased autophagy and therefore induced apoptosis in HL-60-N2 cells with morphological changes, but had no effect on cell viability in HL-60-N1 cells. The neutrophil-regulating efficacy of berberine was confirmed in the urethane-induced lung carcinogenic model and H22 liver cancer allograft model. Furthermore, we found that DOX-derived neutrophils had high levels of CD133 and CD309 surface expression, which prevented both chemotherapeutic sensitivity and immune rejection by self-expression of PD-L1 and surface expression of PD-1 receptor on T cells, whereas berberine could downregulate CD133 and CD309 surface expression. Finally, berberine-relevant targets and pathways were evaluated. This study first suggests an important role of berberine in regulating neutrophil phenotypes to maintain cancer cell sensitivity to DOX.

Exploration of Different Rehabilitation Routes for Sepsis Survivors with Monitoring of Health Status and Quality of Life: RehaSep Trial Protocol

Introduction

This project addresses the important problem of sepsis sequelae resulting in frequent hospital readmissions and higher mortality rate in the post-discharge period. However, neither specific diagnostic methods nor standards for rehabilitation of sepsis patients have been introduced yet. The aim of this study is to evaluate the effectiveness of two different multiparameter-monitored rehabilitation treatments in order to improve the health status and quality of life of sepsis survivors.

Methods

Decades of failed randomized controlled trials involving sepsis patients strongly suggest the need for a paradigm change. Therefore, we designed a prospective, interventional, controlled, pragmatic, patient-centred trial based on the principles of personalized medicine. Sixty post-sepsis patients after hospital discharge will be individually assigned to a control group (without intervention) and two groups with 3-month diagnostically monitored rehabilitation programs based either on the recumbent cycloergometer training or on the experimental hyperbaric oxygen therapy. In all of the patients a wide range of physiological (spirometry, ECG/cycloergometer exercise test), haematological (microscopy) and biochemical (blood tests) parameters will be assessed at hospital discharge and during subsequent 3 months in order to monitor changes of their physical capacity, immunity and degree of post-sepsis organ damage/recovery. For quality of life monitoring a novel tool—“Life After Sepsis Survey”—will be applied.

Planned Outcomes

A set of composite quantitative indices resulting from laboratory measurement data combined with the quality of life questionnaire data will constitute the primary outcomes whereas mortality rate and hospital readmission number will be counted as the secondary outcomes.

Conclusions

Critical analysis of past trials prompted us to implement multiple improvements in tools and procedures. The results of this trial will contribute to the development of rehabilitation therapy addressing not only weakness but also organ damage problems of sepsis survivors.

Trial Registration

ANZCTR (http://www.anzctr.org.au): ACTRN12618000347268, U1111-1210-6110.

Funding

This research was funded by the National Science Center, Poland.

Emodin regulates neutrophil phenotypes to prevent hypercoagulation and lung carcinogenesis

BACKGROUND

Hypercoagulation and neutrophilia are described in several cancers, however, whether they are involved in lung carcinogenesis is currently unknown. Emodin is the main bioactive component from Rheum palmatum and has many medicinal values, such as anti-inflammation and anticancer. This study is to investigate the contributions of neutrophils to the effects of emodin on hypercoagulation and carcinogenesis.

METHODS

The effects of emodin on neutrophil phenotypes were assessed by cell proliferation, morphological changes, phagocytosis and autophagy in vitro. The anti-coagulation and cancer-preventing actions of emodin were evaluated in the urethane-induced lung carcinogenic model. The expressions of Cit-H3 and PAD4 in lung sections were assessed by immunohistochemistry, CD66b⁺ neutrophils were distinguished by immunofluorescence, and cytokines and ROS were examined with ELISA. The neutrophils-regulating and hypercoagulation-improving efficacies of emodin were confirmed in a Lewis lung cancer allograft model. The related targets and pathways of emodin were predicted by network pharmacology.

RESULTS

In vitro, emodin at the dose of 20 µM had no effect on cell viability in HL-60N1 but increased ROS and decreased autophagy and thus induced apoptosis in HL-60N2 with the morphological changes. In the urethane-induced lung carcinogenic model, before lung carcinogenesis, urethane induced obvious hypercoagulation which was positively correlated with lung N2 neutrophils. There were the aggravated hypercoagulation and lung N2 neutrophils after lung carcinoma lesions. Emodin treatment resulted in the ameliorated hypercoagulation and lung carcinogenesis accompanied by the decreased N2 neutrophils (CD66b⁺) in the alveolar cavity. ELISA showed that there were more IFN-γ, IL-12 and ROS and less IL-6, TNF-α and TGF-β1 in the alveolar cavity in the emodin group than those in the control group. Immunohistochemical analysis showed that emodin treatment decreased Cit-H3 and PAD4 in lung sections. In the Lewis lung cancer allograft model, emodin inhibits tumor growth accompanied by the attenuated coagulation and intratumor N2 neutrophils. Network pharmacology indicated the multi-target roles of emodin in N2 neutrophil activation.

CONCLUSIONS

This study suggests a novel function of emodin, whereby it selectively suppresses N2 neutrophils to prevent hypercoagulation and lung carcinogenesis.

Hyperbaric oxygen therapy: Antimicrobial mechanisms and clinical application for infections

Hyperbaric oxygen therapy (HBOT) is a treatment procedure that involves breathing 100% O₂ for a certain time and under a certain pressure. HBOT is commonly administrated as a primary or alternative therapy for different diseases such as infections. In this paper, we reviewed the general aspect of HBOT procedures, the mechanisms of antimicrobial effects and the application in the treatment of infections. Parts of the antimicrobial effects of HBOT are believed to result of reactive from the formation of reactive oxygen species (ROS). It is also said that HBOT enhances the antimicrobial effects of the immune system and has an additive or synergistic effect with certain antimicrobial agents. HBOT has been described as a useful procedure for different infections, particularly in deep and chronic infections such as necrotizing fasciitis, osteomyelitis, chronic soft tissue infections, and infective endocarditis. The anti-inflammation property of HBOT has demonstrated that it may play a significant role in decreasing tissue damage and infection expansion. Patients treated by HBOT need carful pre-examination and monitoring. If safety standards are strictly tracked, HBOT can be considered a suitable procedure with an apt rate of complication.

The effects of hyperbaric oxygen therapy on neuropathic pain via mitophagy in microglia

Purpose

Hyperbaric oxygen (HBO) therapy has been suggested to palliate neuropathic pain, but the mechanisms involved are not well understood. This study explored the involvement of microglial mitophagy via HBO relative to neuropathic pain therapy.

Materials and methods

A total of 80 male Sprague Dawley rats were randomly divided into two groups: a normal group (n = 40) and a mitophagy inhibitor group (n = 40) in which the mitophagy inhibitor cyclosporin A (CsA) was administrated prior to chronic constriction injury (CCI). Groups (n = 10 rats per group) consisted of the following: control (C), sham operation (S), sciatic nerve with chronic constriction injury (CCI), and a CCI plus HBO treatment (CCI + HBO). Pain-related behaviors were evaluated using mechanical withdraw tendency and thermal withdraw latency analysis. Mitochondrial membrane potential was measured, and Western blot was employed to assess expression of NIX and BNIP3. Immunofluorescence changes in neuron protein (NESTIN) and mitochondria inner or outer layer proteins (TIM23, TOM20) were examined.

Results

HBO significantly ameliorated pain-related behaviors, which were downregulated by mitophagy inhibitors (P < 0.05). Mitochondrial membrane potential indexes were decreased after HBO therapy, but were reversed in the mitophagy inhibitor group (P < 0.05). HBO upregulated NIX and BNIP3 expression, which did not occur in the CCI group (P < 0.05). However, expression was reduced when mitophagy inhibitors were administered. Immunofluorescence examination showed that mitophagy in microglia was induced by CCI, which was upregulated after HBO treatment. This phenomenon was not observed in the mitophagy inhibitor group.

Conclusions

HBO therapy palliated CCI-induced neuropathic pain in rats by upregulating microglial mitophagy. These results could serve as guidelines to improve neuropathic pain therapy using HBO to maximize therapeutic efficiency.

Regulation of Sterol Biosynthesis in the Human Fungal Pathogen Aspergillus fumigatus: Opportunities for Therapeutic Development

Sterols are a major component of eukaryotic cell membranes. For human fungal infections caused by the filamentous fungus Aspergillus fumigatus, antifungal drugs that target sterol biosynthesis and/or function remain the standard of care. Yet, an understanding of A. fumigatus sterol biosynthesis regulatory mechanisms remains an under developed therapeutic target. The critical role of sterol biosynthesis regulation and its interactions with clinically relevant azole drugs is highlighted by the basic helix loop helix (bHLH) class of transcription factors known as Sterol Regulatory Element Binding Proteins (SREBPs). SREBPs regulate transcription of key ergosterol biosynthesis genes in fungi including A. fumigatus. In addition, other emerging regulatory pathways and target genes involved in sterol biosynthesis and drug interactions provide additional opportunities including the unfolded protein response, iron responsive transcriptional networks, and chaperone proteins such as Hsp90. Thus, targeting molecular pathways critical for sterol biosynthesis regulation presents an opportunity to improve therapeutic options for the collection of diseases termed aspergillosis. This mini-review summarizes our current understanding of sterol biosynthesis regulation with a focus on mechanisms of transcriptional regulation by the SREBP family of transcription factors.

Hyperbaric Environment: Oxygen and Cellular Damage versus Protection

The elevation of tissue pO2 induced by hyperbaric oxygen (HBO) is a physiological stimulus that elicits a variety of cellular responses. These effects are largely mediated by, or in response to, an increase in the production of reactive oxygen and nitrogen species (RONS). The major consequences of elevated RONS include increased oxidative stress and enhanced antioxidant capacity, and modulation of redox-sensitive cell signaling pathways. Interestingly, these phenomena underlie both the therapeutic and potentially toxic effects of HBO. Emerging evidence indicates that supporting mitochondrial health is a potential method of enhancing the therapeutic efficacy of, and preventing oxygen toxicity during, HBO. This review will focus on the cellular consequences of HBO, and explore how these processes mediate a delicate balance of cellular protection versus damage. © 2017 American Physiological Society. Compr Physiol 7:213-234, 2017.

Wound Healing Devices Brief Vignettes

Significance: The demand for wound care therapies is increasing. New wound care products and devices are marketed at a dizzying rate. Practitioners must make informed decisions about the use of medical devices for wound healing therapy. This paper provides updated evidence and recommendations based on a review of recent publications. Recent Advances: The published literature on the use of medical devices for wound healing continues to support the use of hyperbaric oxygen therapy, negative pressure wound therapy, and most recently electrical stimulation. Critical Issue: To inform wound healing practitioners of the evidence for or against the use of medical devices for wound healing. This information will aid the practitioner in deciding which technology should be accepted or rejected for clinical use. Future Directions: To produce high quality, randomized controlled trials or acquire outcome-based registry databases to further test and improve the knowledge base as it relates to the use of medical devices in wound care.

Short-term hyperoxia does not exert immunologic effects during experimental murine and human endotoxemia

Oxygen therapy to maintain tissue oxygenation is one of the cornerstones of critical care. Therefore, hyperoxia is often encountered in critically ill patients. Epidemiologic studies have demonstrated that hyperoxia may affect outcome, although mechanisms are unclear. Immunologic effects might be involved, as hyperoxia was shown to attenuate inflammation and organ damage in preclinical models. However, it remains unclear whether these observations can be ascribed to direct immunosuppressive effects of hyperoxia or to preserved tissue oxygenation. In contrast to these putative anti-inflammatory effects, hyperoxia may elicit an inflammatory response and organ damage in itself, known as oxygen toxicity. Here, we demonstrate that, in the absence of systemic inflammation, short-term hyperoxia (100% O2 for 2.5 hours in mice and 3.5 hours in humans) does not result in increased levels of inflammatory cytokines in both mice and healthy volunteers. Furthermore, we show that, compared with room air, hyperoxia does not affect the systemic inflammatory response elicited by administration of bacterial endotoxin in mice and man. Finally, neutrophil phagocytosis and ROS generation are unaffected by short-term hyperoxia. Our results indicate that hyperoxia does not exert direct anti-inflammatory effects and temper expectations of using it as an immunomodulatory treatment strategy.

Hyperbaric hyperoxia alters innate immune functional properties during NASA Extreme Environment Mission Operation (NEEMO)

BACKGROUND

Spaceflight is associated with immune dysregulation which is considered as risk factor for the performance of exploration-class missions. Among the consequences of confinement and other environmental factors of living in hostile environments, the role of different oxygen concentrations is of importance as either low (e.g. as considered for lunar or Martian habitats) or high (e.g. during extravehicular activities) can trigger immune dysfunction. The aim of this study was to investigate the impact of increased oxygen availability--generated through hyperbaricity--on innate immune functions in the course of a 14 days NEEMO mission.

METHODS

6 male subjects were included into a 14 days undersea deployment at the Aquarius station (Key Largo, FL, USA). The underwater habitat is located at an operating depth of 47 ft. The 2.5 times higher atmospheric pressure in the habitat leads to hyperoxia. The collection of biological samples occurred 6 days before (L-6), at day 7 (MD7) and 11/13 (MD11/13) during the mission, and 90 days thereafter (R). Blood analyses included differential blood cell count, ex vivo innate immune activation status and inhibitory competences of granulocytes.

RESULTS

The absolute leukocyte count showed an increase during deployment as well as the granulocyte and monocyte count. Lymphocyte count was decreased on MD7. The assessments of native adhesion molecules on granulocytes (CD11b, CD62L) indicated a highly significant cellular activation (L-6 vs. MD7/MD13) during mission. In contrast, granulocytes were more sensitive towards anti-inflammatory stimuli (adenosine) on MD13.

CONCLUSION

Living in the NEEMO habitat for 14 days induced significant immune alterations as seen by an activation of adhesion molecules and vice versa higher sensitivity towards inhibition. This investigation under hyperbaric hyperoxia is important especially for Astronauts' immune competence during extravehicular activities when exposed to similar conditions.

Effects of hyperbaric oxygen on Pseudomonas aeruginosa susceptibility to imipenem and macrophages

BACKGROUND

The seriousness to treat burn wounds infected with Pseudomonas aeruginosa led us to examine whether the effect of the carbapenem antibiotic imipenem is enhanced by hyperbaric oxygen (HBO).

MATERIALS & METHODS

The effects of HBO (100% O2, 3 ATA, 5 h) in combination with imipenen on bacterial counts of six isolates of P. aeruginosa and bacterial ultrastructure were investigated. Infected macrophages were exposed to HBO (100% O2, 3 ATA, 90 min) and the production of reactive oxygen species monitored.

RESULTS

HBO enhanced the effects of imipenen. HBO increased superoxide anion production by macrophages and likely kills bacteria by oxidative mechanisms.

CONCLUSION

HBO in combination with imipenem can be used to kill P. aeruginosa in vitro and such treatment may be beneficial for the patients with injuries containing the P. aeruginosa.

Hyperbaric oxygen enhances neutrophil apoptosis and their clearance by monocyte-derived macrophages

Neutrophil apoptosis and clearance by macrophages are essential for wound healing. Evidence suggests that hyperbaric oxygen (HBO) exposure may enhance neutrophil apoptosis, but HBO effects leading to neutrophil clearance by macrophages are still unclear. In the current study, bovine neutrophils and monocyte-derived macrophages (MDMΦ) were co-cultured under HBO (97.9% O2, 2.1% CO2 at 2.4 atm absolute (ATA)) (1 atm = 101.325 kPa), hyperbaric normoxia (8.8% O2 at 2.4 ATA), normobaric hyperoxia (95% O2, 5% CO2), normoxia (air), and normobaric hypoxia (5% O2, 5% CO2). Phagocytosis of fresh and 22 h aged neutrophils by MDMΦ was increased after HBO pre-treatment, assessed using flow cytometry and light microscopy. Enhanced clearance of neutrophils was accompanied by an increase in H2O2 levels following HBO pre-treatment with upregulation of IL-10 (anti-inflammatory cytokine) mRNA expression in LPS-stimulated MDMΦ that had ingested aged neutrophils. TNF-α (pro-inflammatory cytokine) gene expression did not change in LPS-stimulated MDMΦ that had ingested fresh or aged neutrophils after HBO, pressure, and hyperoxia. These findings suggest that HBO-activated MDMΦ participate in the clearance of apoptotic cells. Uptake of neutrophils by MDMΦ exposed to HBO may contribute to resolution of inflammation, because HBO induced up-regulation of IL-10 mRNA expression.